The present invention relates to a magnetic disk apparatus, and more particularly relates to a magnetic disk apparatus having an improved flexible printed circuit board incorporated into the housing thereof.
In magnetic disk apparatuses, reduction in size of the whole construction, and increase in storage capacity thereof have been rapidly achieved. A representative attempt to reduce magnetic disk apparatuses in size is disclosed in Japanese patent unexamined publication No. 62-283465, in which a flexible printed circuit board is mounted to a head arm, and a pre-amplifier is arranged on the flexible printed circuit board to be received in a recess in the head arm.
In magnetic disk apparatuses, an increase in storage capacity raises a problem in that the control of positioning of the magnetic head and mounting of the pre-amplifier become harder. An increase in storage capacity can be usually achieved by increasing the number of magnetic disks, but the increase of the number of magnetic disks in turn results in increases in number of both the magnetic heads and pre-amplifiers which amplify signals read by the magnetic heads. Particularly, conventional large scale integrated pre-amplifiers limit the number of magnetic heads, which perform signal processing, to six, for example. Accordingly, the number of pre-amplifiers must be increased as the number of magnetic disks and that of magnetic heads increase.
In the attempt of Japanese unexamined patent publication 62(1987)-283465, pre-amplifiers are mounted on head arms, and hence an increase in number of pre-amplifiers enlarges the moment of inertia of the head arms, so that the magnetic heads are deteriorated in accuracy of positioning. When the whole apparatus is reduced in size by down sizing the magnetic disks from 5 inches to 3.5 inches, the head arms also becomes small sized, and thus it becomes very difficult to mount pre-amplifiers to head arms.